JP4090377B2 - Optical recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an optical recording medium, and more particularly to a write-once type optical recording medium.
[0002]
[Prior art]
  Conventionally, optical recording media represented by CDs and DVDs are widely used as recording media for recording digital data. These optical recording media include optical recording media (ROM type optical recording media) that cannot add or rewrite data, such as CD-ROMs and DVD-ROMs, and data recording such as CD-Rs and DVD-Rs. An optical recording medium of a type that can be additionally written but cannot be rewritten (a write-once type optical recording medium), and an optical recording medium of a type that can be rewritten such as a CD-RW or DVD-RW (rewritable optical recording medium) ) And can be broadly divided.
[0003]
  In a ROM type optical recording medium, data is generally recorded by a pit row formed on a substrate in advance at the time of manufacture. In a rewritable type optical recording medium, for example, a phase change material is used as a material for a recording layer. In general, data is recorded using a change in optical characteristics based on a change in the phase state.
[0004]
  In contrast, write-once optical recording media use organic dyes such as cyanine dyes, phthalocyanine dyes, and azo dyes as recording layer materials, and their chemical changes (sometimes in addition to chemical changes, physical changes) In general, data is recorded by using a change in optical characteristics based on a change in the optical characteristics. Unlike write-once optical recording media, write-once optical recording media cannot be erased or rewritten once data has been recorded, but this means that data cannot be tampered with. It plays an important role in applications that require falsification prevention.
[0005]
  However, since the organic dye is deteriorated by irradiation with sunlight or the like, it is desirable that the recording layer is made of a material other than the organic dye in order to further improve the reliability for long-term storage in the write-once type optical recording medium.
[0006]
  As an example in which the recording layer is composed of a material other than an organic dye, a technique is known in which two reaction layers made of an inorganic material are stacked and used as the recording layer, as described in Patent Document 1. .
[0007]
[Patent Document 1]
  JP 62-204442 A
[Problems to be solved by the invention]
  However, the write-once type optical recording medium described in Patent Document 1 is difficult to maintain the initial recording information recorded in the recording layer in a good state for a long time, and the surface property of the recording layer is not necessarily good. Therefore, there were cases where the initial recording characteristics were not good.
[0008]
  The present invention has been made in view of the above problems, and an object of the present invention is to provide a write-once type optical recording medium having good initial characteristics and capable of storing recorded information in a good state over a long period of time.
[0009]
[Means for Solving the Problems]
  The present inventionPurposeIncludes at least a substrate and a recording layer provided on the substrate, and the recording layer includes a first reaction layer containing titanium (Ti) as a main component, silicon (Si), germanium (Ge), carbon (C), a second reaction layer containing as a main component one element selected from the group consisting of tin (Sn), gold (Au), zinc (Zn), and copper (Cu).The above This is achieved by an optical recording medium characterized in that 25 atomic% or more and less than 50 atomic% of aluminum (Al) is added to one reaction layer..
[0010]
  According to the present invention, good initial characteristics can be obtained, and long-term storage reliability can be improved. In the first reaction layer25 atomic% or more and less than 50 atomic%Aluminum (Al) is addedFromJitter can be suppressed to a lower level and a high degree of modulation can be obtained.
[0011]
  Further, it is preferable to further include a first dielectric layer and a second dielectric layer provided so as to sandwich the recording layer, and further includes a light transmission layer provided on the side opposite to the substrate when viewed from the recording layer. The thickness of the light transmission layer is preferably set to 10 to 300 μm. Such a structure having a thin light transmission layer is a so-called next-generation optical recording medium, and a laser beam for recording and reproduction is irradiated from the light transmission layer side. The wavelength of the laser beam is preferably 380 nm to 450 nm. This is because a particularly high degree of modulation can be obtained when recording is performed using a laser beam having a wavelength of 380 nm to 450 nm.
[0012]
  Of the present inventionThe purpose is alsoA recording layer included in a predetermined information layer different from the information layer farthest from the light transmission layer among the plurality of information layers, the recording layer including a substrate and a plurality of information layers provided on the substrate, A first reaction layer containing Ti) as a main component and silicon (Si), germanium (Ge), carbon (C), tin (Sn), gold (Au), zinc (Zn), and copper (Cu) And a second reaction layer containing as a main component one element selected from the groupThus, the optical recording medium is characterized in that 25 atomic% or more and less than 50 atomic% of aluminum (Al) is added to the first reaction layer..
[0013]
  According to the present invention, in addition to the effects described above, since the light transmittance of the predetermined information layer is high, recording of data on the information layer located on the opposite side of the light transmission layer as viewed from the predetermined information layer and Does not interfere with regeneration.
[0014]
  The information layer located on the side opposite to the light incident surface when viewed from the predetermined information layer is an information layer capable of recording and / or reproducing data by irradiating a laser beam having a wavelength of 380 nm to 450 nm. Preferably there is. Since the difference between the light transmittance of the portion where the recording mark is formed and the light transmittance of the other portion is very small in the above wavelength region, the predetermined information layer is light as viewed from the predetermined information layer. It becomes possible to stably record and / or reproduce data with respect to the information layer located on the side opposite to the incident surface.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0016]
  FIG. 1A is a cutaway perspective view showing the appearance of an optical recording medium 10 according to a preferred embodiment of the present invention, and FIG. 1B is an enlarged view of part A shown in FIG. It is sectional drawing.
[0017]
  An optical recording medium 10 shown in FIGS. 1A and 1B is a disc-shaped optical recording medium having an outer diameter of about 120 mm and a thickness of about 1.2 mm. As shown in FIG. The support substrate 11, which is a substrate in the present invention, a reflective layer 12, dielectric layers 13 and 15, a recording layer 14, and a light transmission layer 16 are provided. The optical recording medium 10 according to the present embodiment irradiates the recording layer 14 with a laser beam L having a wavelength λ of, for example, 380 nm to 450 nm, preferably about 405 nm, from the light incident surface 16 a that is the surface of the light transmission layer 16. This is a write-once type optical recording medium capable of recording and reproducing data. In recording and reproducing data with respect to the optical recording medium 10, an objective lens having a numerical aperture of 0.7 or more, preferably about 0.85 is used, whereby the beam spot of the laser beam L on the recording layer 14 is It is squeezed to about 0.4 μm.
[0018]
  The support substrate 11 is a disk-shaped substrate having a thickness of about 1.1 mm used for securing a thickness (about 1.2 mm) required for the optical recording medium 10, and has a central portion on one surface thereof. Grooves 11a and lands 11b for guiding the laser beam L are formed in a spiral shape from the vicinity to the outer edge portion or from the outer edge portion to the vicinity of the center portion. Although not particularly limited, the depth of the groove 11a is preferably set to 10 nm to 40 nm, and the pitch of the groove 11a is preferably set to 0.2 μm to 0.4 μm. Various materials can be used as the material of the support substrate 11, and for example, glass, ceramics, or resin can be used. Among these, a resin is preferable from the viewpoint of ease of molding. Examples of such resins include polycarbonate resins, olefin resins, acrylic resins, epoxy resins, polystyrene resins, polyethylene resins, polypropylene resins, silicone resins, fluorine-based resins, ABS resins, and urethane resins. Of these, polycarbonate resins and olefin resins are particularly preferable from the viewpoint of processability. However, since the support substrate 11 does not become an optical path of the laser beam L, it is not necessary to have high light transmittance.
[0019]
  The support substrate 11 is preferably produced by an injection molding method using a stamper, but it can also be produced by other methods such as a photopolymer (2P) method.
[0020]
  The reflection layer 12 plays a role of reflecting the laser beam L incident from the light transmission layer 16 side and emitting the laser beam L from the light transmission layer 16 again. The material of the reflective layer 12 is not particularly limited as long as it can reflect the laser beam L. For example, magnesium (Mg), aluminum (Al), titanium (Ti), chromium (Cr), iron (Fe), cobalt (Co ), Nickel (Ni), copper (Cu), zinc (Zn), germanium (Ge), silver (Ag), platinum (Pt), gold (Au), and the like. Among these, metal materials such as aluminum (Al), gold (Au), silver (Ag), copper (Cu), or alloys thereof (such as alloys of Ag and Cu) are used because of their high reflectivity. It is preferable. In the present invention, it is not essential to provide the reflective layer 12 on the optical recording medium. However, if this is provided, a high reproduction signal (C / N ratio) can be easily obtained after the optical recording due to the multiple interference effect. For the purpose of preventing corrosion of the reflective layer 12, a moisture-proof layer made of a dielectric may be interposed between the support substrate 11 and the reflective layer 12.
[0021]
  The thickness of the reflective layer 12 is preferably set to 5 to 300 nm, particularly preferably 20 to 200 nm. This is because, if the thickness of the reflective layer 12 is less than 5 nm, the above-described effect due to the reflective layer 12 cannot be sufficiently obtained. On the other hand, if the thickness of the reflective layer 12 exceeds 300 nm, the surface property of the reflective layer 12 is This is because not only the temperature is lowered, but the film formation time is lengthened and the productivity is lowered. On the other hand, if the thickness of the reflective layer 12 is set to 5 to 300 nm, particularly 20 to 200 nm, the above effect by the reflective layer 12 can be sufficiently obtained, and the surface property can be maintained high. Furthermore, it becomes possible to prevent a decrease in productivity.
[0022]
  The dielectric layers 13 and 15 serve to physically and chemically protect the recording layer 14 provided therebetween, and the recording layer 14 is sandwiched between the dielectric layers 13 and 15 so that optical recording is performed. Thereafter, the deterioration of recorded information is effectively prevented over a long period of time.
[0023]
  The material constituting the dielectric layers 13 and 15 is not particularly limited as long as the material is transparent in the wavelength region of the laser beam L to be used. For example, oxides, sulfides, nitrides, or combinations thereof are mainly used. Although it can be used as a component, from the viewpoint of thermal deformation prevention of the support substrate 11 and the like, and protection characteristics for the recording layer 14, Al₂O₃AlN, ZnO, ZnS, GeN, GeCrN, CeO₂, SiO, SiO₂, Si₃N₄, SiC, La₂O₃, TaO, TiO₂, SiAlON (SiO₂, Al₂O₃, Si₃N₄And a mixture of AlN) and LaSiON (La₂O₃, SiO₂And Si₃N₄Etc.), such as aluminum (Al), silicon (Si), cerium (Ce), titanium (Ti), zinc (Zn), tantalum (Ta), oxides, nitrides, sulfides, carbides or mixtures thereof In particular, ZnS and SiO.₂It is more preferable to use a mixture thereof. In this case, ZnS and SiO₂The molar ratio is particularly preferably set to about 80:20. The dielectric layer 13 and the dielectric layer 15 may be made of the same material, but may be made of different materials. Furthermore, at least one of the dielectric layers 13 and 15 may have a multilayer structure including a plurality of dielectric layers.
[0024]
  Moreover, the layer thickness of the dielectric layers 13 and 15 is not particularly limited, but it is preferable that both are set to 3 to 200 nm. This is because when the layer thickness is less than 3 nm, it is difficult to obtain the above-described effects. On the other hand, when the layer thickness exceeds 200 nm, the film formation time may be increased and the productivity may be reduced. This is because cracks may occur due to the stress of 15.
[0025]
  The dielectric layers 13 and 15 also play a role of expanding the difference in optical characteristics before and after recording, and in order to achieve this, a high refractive index (n) in the wavelength region of the laser beam L used. It is preferable to select a material having Further, when the laser beam L is irradiated, if the energy absorbed by the dielectric layers 13 and 15 is large, the recording sensitivity is lowered. To prevent this, the wavelength region of the laser beam L used is prevented. It is preferable to select a material having a low extinction coefficient (k).
[0026]
  The recording layer 14 is a layer on which an irreversible recording mark is formed. As shown in FIG. 2, a reaction layer 21 located on the support substrate 11 side and a reaction layer 22 located on the light transmission layer 16 side are laminated. It has a structure. The unrecorded region of the recording layer 14 is in a state where the reaction layer 21 and the reaction layer 22 are laminated as shown in FIG. 2, but the laser beam L having a predetermined power or more is irradiated. With the heat, the elements constituting the reaction layer 21 and the elements constituting the reaction layer 22 are partially or wholly mixed to form the recording mark M as shown in FIG. At this time, since the reflectivity with respect to the laser beam L is greatly different between the mixed portion where the recording mark M is formed in the recording layer and the other portion (blank region), data recording / reproduction is performed using this. Can do. The recorded data includes the length of the recording mark M (length from the leading edge to the trailing edge of the recording mark M) and the length of the blank area (from the trailing edge of the recording mark M to the leading edge of the next recording mark M). Length). The lengths of the recording mark M and the blank area are set to an integral multiple of T, where T is a length corresponding to one period of the reference clock. Specifically, in the 1,7RLL modulation system, a recording mark M having a length of 2T to 8T and a blank area are used.
[0027]
  One of the reaction layer 21 and the reaction layer 22 (preferably the reaction layer 21) is made of a material mainly composed of titanium (Ti). Here, the “main component” of the reaction layer means the content ratio (atom%) Refers to the largest element. Therefore, “the reaction layer is made of a material containing titanium (Ti) as a main component” means that the content of titanium (Ti) in the reaction layer is 50atom%That means that. In the reaction layer, it is very preferable that aluminum (Al) is added to titanium (Ti), which is the main component, so that the jitter can be kept low. The amount of aluminum (Al) added is 25.atom%50atom%It is preferable to set to less than. According to this, it is possible to suppress the jitter to a lower level and obtain a high degree of modulation. In addition, it is preferable that one of the reaction layer 21 and the reaction layer 22 is substantially free of elements other than titanium (Ti) and aluminum (Al).
[0028]
  The other of the reaction layer 21 and the reaction layer 22 (preferably the reaction layer 22) is formed of silicon (Si), germanium (Ge), carbon (C), tin (Sn), gold (Au), zinc (Zn) or The main component is copper (Cu). From the viewpoint of increasing the recording sensitivity, the reaction layer has silicon (Si), germanium (Ge), carbon (C), tin (Sn), gold (Au), zinc (Zn), or copper (Cu) as main components. ), Magnesium (Mg), copper (Cu) (except when copper (Cu) is the main component), silver (Ag), gold (Au) (gold (Au) is the main component. Etc.) may be added. The main component of the reaction layer is preferably silicon (Si), germanium (Ge), or tin (Sn), and most preferably silicon (Si).
[0029]
  In summary, the material of the reaction layer 21 is 25 (25%) of aluminum (Al) in titanium (Ti).atom%50atom%It is most preferable to use less added material and to use silicon (Si) as the material of the reaction layer 22. If the reaction layer 21 and the reaction layer 22 are formed of such materials, high reliability for long-term storage can be secured while suppressing environmental load, and high recording sensitivity and low jitter can be obtained. It becomes possible.
[0030]
  As the layer thickness of the recording layer 14 increases, the flatness of the surface 22a of the reaction layer 22 irradiated with the beam spot of the laser beam L deteriorates. As a result, the noise level of the reproduction signal increases and the recording layer 14 is recorded. Sensitivity also decreases. Considering this point, it is effective to set the recording layer 14 to be thin in order to suppress the noise level of the reproduction signal by increasing the flatness of the surface 22a of the reaction layer 22 and increase the recording sensitivity. However, if the thickness is too thin, the difference in optical constants before and after recording decreases, and a high level reproduction signal (C / N ratio) cannot be obtained during reproduction. Also, if the recording layer 14 is set to be extremely thin, it becomes difficult to control the layer thickness during film formation. Considering the above, the thickness of the recording layer 14 is preferably set to 2 to 40 nm, more preferably 2 to 20 nm, and further preferably 2 to 15 nm.
[0031]
  The layer thickness of each of the reaction layer 21 and the reaction layer 22 is not particularly limited, but the noise level of the reproduction signal is sufficiently suppressed, sufficient recording sensitivity is ensured, and the change in reflectance before and after recording is sufficiently increased. In order to achieve this, the thickness is preferably 1 to 30 nm, and the ratio of the layer thickness of the reaction layer 21 to the layer thickness of the reaction layer 22 (layer thickness of the reaction layer 21 / layer thickness of the reaction layer 22) is 0. It is preferable that it is 2-5.0.
[0032]
  The reflective layer 12, the dielectric layer 13, the recording layer 14 (reaction layers 21 and 22), and the dielectric layer 15 may be formed by a vapor phase growth method using chemical species including these constituent elements, for example, A sputtering method or a vacuum deposition method can be used, and among these, the sputtering method is preferably used.
[0033]
  The light transmission layer 16 is a layer that constitutes an incident surface of the laser beam L and serves as an optical path of the laser beam L, and the thickness thereof is preferably set to 10 to 300 μm, and preferably set to 50 to 150 μm. Particularly preferred. The material of the light transmission layer 16 is not particularly limited as long as the material has a sufficiently high light transmittance in the wavelength region of the laser beam L to be used, but it is preferable to use an acrylic or epoxy ultraviolet curable resin. . Moreover, you may form the light transmissive layer 16 using the light transmissive sheet | seat which consists of a light transmissive resin, and various adhesive agents or adhesives instead of the film | membrane which hardens ultraviolet curable resin.
[0034]
  The above is the structure of the optical recording medium 10 according to a preferred embodiment of the present invention.
[0035]
  Next, the principle of data recording on the optical recording medium 10 will be described.
[0036]
  When recording data on the optical recording medium 10, as shown in FIG. 1, the recording layer 14 is irradiated with a laser beam L whose intensity is modulated on the optical recording medium 10 from the light incident surface 16 a. At this time, the numerical aperture (NA) of the objective lens for focusing the laser beam L is set to 0.7 or more, for example, and the wavelength λ of the laser beam L is set to 380 nm to 450 nm, for example. NA) is set to about 0.85, and the wavelength λ of the laser beam L is set to about 405 nm.
[0037]
  When the recording layer 14 is irradiated with such a laser beam L, the recording layer 14 is heated and the elements constituting the reaction layer 21 and the elements constituting the reaction layer 22 are mixed. Such a mixed portion becomes a recording mark M as shown in FIG. 3, and its reflectivity is different from the reflectivity of the other portion (blank area), and this is used to record / reproduce data. Can be performed. In addition, in this embodiment, since the reaction layer 21 and the reaction layer 22 are made of the above-described materials, it is possible to obtain high recording sensitivity and low jitter while ensuring sufficient storage reliability. . In addition, since the materials constituting the reaction layers 21 and 22 are common materials on the earth, it is also possible to suppress environmental loads.
[0038]
  FIG. 4 is a view showing a preferred example of a pulse train pattern of the laser beam L for recording data on the optical recording medium 10, wherein (a) shows a pulse train pattern when a 2T signal is formed, and (b) ) Shows a pulse train pattern when a 3T signal is formed, (c) shows a pulse train pattern when a 4T signal is formed, and (d) shows a pulse train pattern when a 5T signal to 8T signal is formed. .
[0039]
  As shown in FIGS. 4A to 4D, in this pulse train pattern, the set intensity of the laser beam L is modulated into two intensities (binary) consisting of the recording power Pw1 and the base power Pb1 (<Pw1). The
[0040]
  The recording power Pw1 is set to a high level such that the reaction layers 21 and 22 constituting the recording layer 14 are melted and mixed by irradiation, and the base power Pb1 is the recording layer 14 in a heated state even when irradiated. It is set to a very low level so as to be cooled.
[0041]
  As shown in FIG. 4A, when a 2T signal is formed, the number of recording pulses of the laser beam L is set to “1”. The number of recording pulses of the laser beam L is defined by the number of times the intensity of the laser beam L is increased to the recording power Pw1 (or Pw2 (Pw2 will be described later)). More specifically, the intensity of the laser beam L is set to the base power Pb1 before the timing t11, and the period from the timing t11 to the timing t12 (t_top), The recording power Pw1 is set, and after the timing t12, the recording power Pw1 is set again.
[0042]
  Further, as shown in FIG. 4B, when the 3T signal is formed, the number of recording pulses of the laser beam L is set to “2”. That is, the intensity of the laser beam L is the period from the timing t21 to the timing t22 (t_top) And the period from timing t23 to timing t24 (t_lp) Is set to the recording power Pw1, and is set to the base power Pb1 in other periods.
[0043]
  Further, as shown in FIG. 4C, when a 4T signal is formed, the number of recording pulses of the laser beam is set to “3”. That is, the intensity of the laser beam L is a period from the timing t31 to the timing t32 (t_top), The period from timing t33 to timing t34 (t_mp) And the period from timing t35 to timing t36 (t_lp) Is set to the recording power Pw1, and is set to the base power Pb1 in other periods.
[0044]
  Then, as shown in FIG. 4D, when forming the 5T signal to 8T signal, the number of recording pulses of the laser beam L is set to “4” to “7”, respectively. Again, the intensity of the laser beam L is t_top(Period from timing t41 to timing t42), t_mp(A period from timing t43 to timing t44, a period from timing t45 to timing t46, etc.) and t_lpThe recording power Pw1 is set during the period (period from timing t47 to timing t48), and the base power Pb1 is set during the other periods.
[0045]
  As described above, in the region where the recording signal (2T signal to 8T signal) is to be formed, the reaction layers 21 and 22 constituting the recording layer 14 are dissolved and mixed by the irradiation of the laser beam L having the recording power Pw1, and the recording mark is recorded. M is formed.
[0046]
  The recording layer 14 used in the above embodiment has a high light transmittance, and particularly for a laser beam in the wavelength region of 380 nm to 450 nm, the portion where the recording mark M is formed and other portions. It has the characteristic that the light transmittance difference with a part is very small. If attention is paid to this point, it is considered that the recording layer 14 used in the above embodiment is suitable as a recording layer for an optical recording medium in which a plurality of information layers are laminated. Hereinafter, embodiments in which the present invention is applied to an optical recording medium in which a plurality of information layers are laminated will be described.
[0047]
  FIG. 5 is a partial cross-sectional view of an optical recording medium 30 according to another preferred embodiment of the present invention. The external appearance of the optical recording medium 30 according to this embodiment is a disc-shaped optical recording medium having an outer diameter of about 120 mm and a thickness of about 1.2 mm, similar to the optical recording medium 10 shown in FIG. FIG. 5 shows an enlarged view of the A portion.
[0048]
  As shown in FIG. 5, the optical recording medium 30 according to this embodiment is provided between the support base 31, the transparent intermediate layer 32, the light transmission layer 33, and the support base 31 and the transparent intermediate layer 32. An information layer L0, and an information layer L1 provided between the transparent intermediate layer 32 and the light transmission layer 33. The information layer L0 constitutes an information layer far from the light incident surface 33a. An information layer closer to the light incident surface 33a is formed. Thus, the optical recording medium 30 according to the present embodiment has two information layers stacked.
[0049]
  When recording / reproducing data on the information layer L0, the information layer L1 is irradiated with the laser beam L through the information layer L1 closer to the light incident surface 33a, so that the information layer L1 has sufficient light transmittance. It is necessary to have. Specifically, it preferably has a light transmittance of 40% or more at the wavelength of the laser beam L used for data recording / reproduction, and has a light transmittance of 50% or more. Particularly preferred.
[0050]
  The support base 31 is an element corresponding to the support base 11 of the optical recording medium 10 shown in FIG. 1 and may be set to the same thickness using the same material as the support base 11. Grooves 31a and lands 31b are provided on the surface of the support base 31, and these grooves 31a and / or lands 31b serve as guide tracks for the laser beam L when data recording / reproduction is performed on the information layer L0. To play a role.
[0051]
  The transparent intermediate layer 32 serves to separate the information layer L0 and the information layer L1 from each other with a sufficient physical and optical distance, and a groove 32a and a land 32b are provided on the surface thereof. These grooves 32a and / or lands 32b serve as guide tracks for the laser beam L when data is recorded / reproduced with respect to the information layer L1. Although it does not specifically limit as a material of the transparent intermediate | middle layer 32, It is preferable to use an ultraviolet curable acrylic resin. The transparent intermediate layer 32 serves as an optical path of the laser beam L when data is recorded / reproduced with respect to the information layer L0, and therefore needs to have sufficiently high light transmittance.
[0052]
  The light transmissive layer 33 is an element corresponding to the light transmissive layer 16 of the optical recording medium 10 shown in FIG. 1, and a material similar to that of the light transmissive layer 16 can be used as its material. What is necessary is just to set so that the total film thickness with the transparent intermediate | middle layer 32 may become the same thickness as the light transmissive layer 16. FIG.
[0053]
  As shown in FIG. 6, the information layer L <b> 1 has a configuration in which the reflective layer 12 is deleted from each functional layer provided between the support substrate 31 and the light transmission layer 33 of the optical recording medium 30. That is, the recording layer 14 includes the reaction layers 21 and 22 and the two dielectric layers 13 and 15 provided so as to sandwich the recording layer 14. As in the optical recording medium 10 according to the above embodiment, the unrecorded region of the recording layer 14 is a state in which the reaction layer 21 and the reaction layer 22 are stacked as shown in FIG. When the laser beam L having the following power is irradiated, the elements constituting the reaction layer 21 and the elements constituting the reaction layer 22 are partially or wholly mixed and recorded by the heat as shown in FIG. Mark M. Thereby, desired data can be recorded in the information layer L1. The thin reflective layer 12 may be provided on the information layer L1 as long as the light transmittance of the information layer L1 is sufficiently secured.
[0054]
  The materials for the dielectric layers 13 and 15 and the reaction layers 21 and 22 are as described above. That is, one of the reaction layer 21 and the reaction layer 22 (preferably the reaction layer 21) is made of a material mainly composed of titanium (Ti), and the other (preferably the reaction layer 22) is made of silicon (Si) or germanium (Ge). , Carbon (C), tin (Sn), gold (Au), zinc (Zn) or copper (Cu). In particular, as the material of the reaction layer 21, aluminum (Al) is 25 in titanium (Ti).atom%50atom%It is preferable to use less added material and to use silicon (Si) as the material of the reaction layer 22. With the above configuration, the information layer L1 has high recording sensitivity, and jitter of recorded data is sufficiently low. In addition, high storage reliability is ensured.
[0055]
  Moreover, since the recording layer 14 is made of the above material, the information layer L1 can ensure a high light transmittance, specifically, a light transmittance of 50% or more. For this reason, it is possible to increase the sensitivity in recording data on the information layer L0.
[0056]
  Further, since the recording layer 14 is made of the above material, the information layer L1 has a light transmittance of a portion in a laminated state (portion other than the recording mark M) particularly with respect to a laser beam in a wavelength region of 380 nm to 450 nm. The difference from the light transmittance of the mixed portion (the portion where the recording mark M is formed) is very small. Specifically, when the wavelength λ of the laser beam L is 380 nm to 450 nm, the difference in light transmittance between the stacked portion and the mixed portion can be 2% or less, and in particular, the next generation type optical recording medium For the laser beam having the wavelength λ = about 405 nm used in the above, the light transmittance difference between the laminated portion and the mixed portion can be 1.6% or less. Thus, when data is recorded / reproduced with respect to the information layer L0, the beam spot formed on the information layer L1 is an unrecorded area (area where the recording mark M does not exist) or a recorded area (a large number of areas). The recording beam M is recorded / reproduced with respect to the information layer L0 because the intensity of the laser beam L reaching the information layer L0 is hardly changed depending on whether the recording mark M is formed on the recording layer M or the boundary line. Can be performed stably.
[0057]
  Although the configuration of the information layer L0 is not particularly limited, the configuration can be the same as the configuration between the support substrate 11 and the light transmission layer 16 of the optical recording medium 10 (see FIG. 2). The information layer L0 does not have to be a write-once information layer, and may be a read-only information layer that does not include a recording layer, for example. In this case, a spiral prepit is provided on the support base 31, and information is held in the information layer L0 by the prepit.
[0058]
  FIG. 8 is a diagram showing a preferable example of a pulse train pattern of the laser beam L for recording data on the information layer L1 of the optical recording medium 30, and FIG. 8A shows a pulse train pattern when a 2T signal is formed. (B) shows a pulse train pattern when a 3T signal is formed, (c) shows a pulse train pattern when a 4T signal is formed, and (d) shows a pulse train pattern when a 5T signal to 8T signal is formed. Is shown.
[0059]
  As shown in FIGS. 8A to 8D, in this pulse train pattern, the intensity of the laser beam L is modulated into three set intensities (ternary values) composed of the recording power Pw2, the intermediate power Pm2, and the base power Pb2. The
[0060]
  Regarding the relationship between the recording power Pw2, the intermediate power Pm2, and the base power Pb2,
Pw2> Pm2> Pb2
Set to The recording power Pw2 is set to a high level such that the reaction layers 21 and 22 included in the information layer L1 are melted and mixed by irradiation, and the intermediate power Pm2 and the base power Pb2 are included in the information layer L1 even when irradiated. The reaction layers 21 and 22 are set at a low level so as not to melt and mix. In particular, the base power Pb2 has almost no thermal influence on the reaction layers 21 and 22 by irradiation, and the reaction layers 21 and 22 heated by irradiation with the laser beam L having the recording power Pw2 are extremely cooled. Set to a low level.
[0061]
  As shown in FIG. 8A, when a 2T signal is formed, the number of recording pulses of the laser beam L is set to “1”, and then the cooling period t_clIs inserted. That is, the intensity of the laser beam L is set to the intermediate power Pm2 before the timing t51, and the period from the timing t51 to the timing t52 (t_top) Is set to the recording power Pw2, and the period t from timing t52 to timing t53 is set._clIs set to the base power Pb2, and after the timing t53, it is set to the intermediate power Pm2.
[0062]
  Further, as shown in FIG. 8B, when forming a 3T signal, the number of recording pulses of the laser beam L is set to “2”, and then the cooling period t_clIs inserted. That is, the intensity of the laser beam L is set to the intermediate power Pm2 before the timing t61, and the period from the timing t61 to the timing t62 (t_top) And a period from timing t63 to timing t64 (t_lp) Is set to the recording power Pw2, and the period from the timing t62 to the timing t63 (t_off) And a period from timing t64 to timing t65 (t_cl) Is set to the base power Pb2, and after the timing t65, it is set to the intermediate power Pm2.
[0063]
  Further, as shown in FIG. 8C, when forming a 4T signal, the number of recording pulses of the laser beam is set to “3”, and then the cooling period t_clIs inserted. That is, the intensity of the laser beam L is set to the intermediate power Pm2 before the timing t71, and the period from the timing t71 to the timing t72 (t_top), A period from timing t73 to timing t74 (t_mp) And the period from timing t75 to timing t76 (t_lp) Is set to the recording power Pw2, and the period from the timing t72 to the timing t73 (t_off), A period from timing t74 to timing t75 (t_off) And a period from timing t76 to timing t77 (t_cl) Is set to the base power Pb2, and after the timing t77, it is set to the intermediate power Pm2.
[0064]
  As shown in FIG. 8D, when forming 5T signal to 8T signal, the number of recording pulses of the laser beam L is set to “4” to “7”, respectively, and then the cooling period t_clIs inserted. Therefore, the number of multi-pulses is set to “2” to “5” when forming 5T signals to 8T signals, respectively. Again, the intensity of the laser beam L is t_top(Period from timing t81 to timing t82), t_mp(A period from timing t83 to timing t84, a period from timing t85 to timing t86, etc.) and t_lpIn the period (period from timing t87 to timing t88), the recording power Pw2 is set and the off period t_off(Period from timing t82 to timing t83, period from timing t86 to timing t87, etc.) and cooling period t_clIn the (period from timing t88 to timing t89), the base power Pb2 is set, and in other periods, the intermediate power Pm2 is set.
[0065]
  As described above, in the region where the recording signal (2T signal to 8T signal) is to be formed, the reaction layers 21 and 22 included in the information layer L1 are melted and mixed by irradiation with the laser beam L having the recording power Pw2, and the desired layer is formed. A recording mark M having a length is formed.
[0066]
  The reason why it is preferable to use the pulse train pattern shown in FIG. 8 in recording data on the information layer L1 is as follows.
[0067]
  That is, as described above, since the information layer L1 does not include the reflective layer (or only a very thin reflective layer is provided), the heat dissipation effect by the reflective layer cannot be obtained at all (or sufficiently). For this reason, in the pulse train pattern shown in FIG. 4, the heat by the laser beam L is not sufficiently dissipated, and this may deteriorate the signal characteristics. However, if the pulse train pattern shown in FIG. 8 is used for recording data on the information layer L1, the intensity of the laser beam L is set to the base power Pb2 immediately after the recording pulse, so that heat may be accumulated excessively. As a result, good signal characteristics can be obtained.
[0068]
  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.
[0069]
  For example, the optical recording media 10 and 30 according to each of the above embodiments are so-called next-generation optical recording media that are irradiated with a laser beam via a very thin light transmission layer. The possible optical recording media are not limited to this, and the present invention can also be applied to DVD-type optical recording media and CD-type optical recording media.
[0070]
  In the optical recording media 10 and 30 according to the above embodiments, the recording layer 14 is composed of only two reaction layers 21 and 22. However, the recording layer includes other layers such as a third reaction layer and a dielectric layer. A body layer may be included.
[0071]
  Furthermore, although the optical recording medium 30 described above includes two stacked information layers (L0, L1), the optical recording includes three or more stacked information layers (L0, L1, L2,...). The present invention can also be applied to a medium. In this case, if the recording layer included in the information layer closer to the light incident surface is configured as described above, data recording / reproduction with respect to the lower information layer can be stably performed.
[0072]
【Example】
  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
[0073]
  [Sample Preparation 1]
  An optical recording medium sample having the same configuration as the optical recording medium 10 shown in FIGS. 1 and 2 was produced by the following method.
[0074]
  First, a disk-shaped support substrate 11 made of polycarbonate having a thickness of 1.1 mm and a diameter of 120 mm and having a groove 11a and a land 11b formed on the surface was produced by an injection molding method.
[0075]
  Next, the support substrate 11 is set in a sputtering apparatus, and the surface on which the grooves 11a and lands 11b are formed is made of an alloy of silver (Ag), palladium (Pd), and copper (Cu) with a thickness of 100 nm. Reflective layer 12, ZnS and SiO₂A dielectric layer 13 made of a mixture (molar ratio = 80: 20) having a thickness of 26 nm, titanium (Ti) as a main component, and aluminum (Al) being 43atom%5 nm thick reaction layer 21 made of added material, 5 nm thick reaction layer 22 made of silicon (Si), ZnS and SiO 2₂A dielectric layer 15 having a thickness of 30 nm made of a mixture (molar ratio = 80: 20) was sequentially formed by sputtering.
[0076]
  Next, an acrylic ultraviolet curable resin was coated on the dielectric layer 15 by spin coating, and this was irradiated with ultraviolet rays to form a light transmission layer 16 having a thickness of 100 μm. Thereby, the optical recording medium sample of Example 1 was completed.
[0077]
  Next, as a material of the reaction layer 21, copper (Cu) is the main component, and aluminum (Al) and gold (Au) are each 23.atom%, 13atom%An optical recording medium sample of Comparative Example 1 was produced in the same manner as in Example 1 except that the added material was used.
[0078]
  [Sample Evaluation 1]
  The optical recording medium samples of Example 1 and Comparative Example 1 were stored in an environment where the temperature was 80 ° C. and the humidity was 85%, after 0 hours (the state before storage in the above environment), after 100 hours, and after 200 hours. And a storage reliability test (storage test) was performed by measuring the reflectance and jitter after 300 hours.
[0079]
  The reflectance and jitter were measured under the following conditions.
[0080]
  First, the optical recording medium samples of Example 1 and Comparative Example 1 in each storage stage (0 hour, 100 hours, 200 hours, 300 hours) are set in an optical recording medium evaluation apparatus (trade name: DDU1000, manufactured by Pulstec). The recording layer 14 (reaction layers 21 and 22) is irradiated with a laser beam having a wavelength of 405 nm through an objective lens having a numerical aperture of 0.85 while rotating at a linear velocity of 4.9 m / sec. A mixed signal composed of 2T to 8T was recorded using the pulse train pattern shown in FIG. The pulse width is t_topIs set to 0.7T and t_mpIs set to 0.5T and t_lpWas set to 0.5T. The recording power Pw1 of the laser beam L was set to 4.4 mW for the optical recording medium sample of Example 1, and 4.8 mW for the optical recording medium sample of Comparative Example 1. The base power Pb1 was set to 1.0 mW in all cases.
[0081]
  Next, the mixed signal recorded after 0 hours and the mixed signal recorded in the storage stage were reproduced to measure jitter, and the reflectance between recording marks (blank area) was measured. Here, “jitter” refers to clock jitter, “fluctuation (σ)” of a reproduction signal is obtained by a time interval analyzer, and is calculated by σ / Tw (Tw: one cycle of the clock).
[0082]
  FIG. 9 shows the measurement result for the reflectance, and FIG. 10 shows the measurement result for the jitter. In FIGS. 9 and 10, the reflectance and jitter of the mixed signal recorded after 0 hours are expressed as “Achival”, and the reflectance and jitter of the mixed signal recorded in the storage stage are expressed as “Shelf”.
[0083]
  As shown in FIG. 9, in the optical recording medium sample of Comparative Example 1, the reflectance gradually decreased as the storage test progressed. However, in the optical recording medium sample of Example 1, the reflectance decreased almost by the storage test. I couldn't see it. Further, as shown in FIG. 10, in the optical recording medium sample of Comparative Example 1, the jitter increased as the storage test progressed, but in the optical recording medium sample of Example 1, an increase in jitter due to the storage test was observed. There wasn't.
[0084]
  From the above, it was confirmed that the optical recording medium sample of Example 1 has very high storage reliability.
[0085]
  [Sample Preparation 2]
  An optical recording medium sample having a structure in which the reflective layer 12 was deleted from the optical recording medium 10 shown in FIGS. 1 and 2 was produced by the following method.
[0086]
  First, a disk-shaped support substrate 11 made of polycarbonate having a thickness of 1.1 mm and a diameter of 120 mm and having a groove 11a and a land 11b formed on the surface was produced by an injection molding method.
[0087]
  Next, the support substrate 11 is set in a sputtering apparatus, and ZnS and SiO2 are formed on the surface on which the groove 11a and the land 11b are formed.₂25 nm thick dielectric layer 13 made of a mixture (molar ratio = 80: 20), 5 nm thick reaction layer 21 made of titanium (Ti), 4 nm thick reaction layer 22 made of silicon (Si), TiO 2₂A dielectric layer 15 having a thickness of 33 nm was sequentially formed by sputtering.
[0088]
  Next, an acrylic ultraviolet curable resin was coated on the dielectric layer 15 by spin coating, and this was irradiated with ultraviolet rays to form a light transmission layer 16 having a thickness of 100 μm. ThisComparative Example 2An optical recording medium sample was completed. Such an optical recording medium sample can be considered as a structure in which the information layer L0 is omitted from the optical recording medium 30 shown in FIGS. 5 and 6, that is, a structure including only the information layer L1.
[0089]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 85.0 atomic%, Al = 15.0 atomic%) was used as a material for the reaction layer 21.Comparative Example 2LikeComparative Example 2-0An optical recording medium sample was prepared.
[0090]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 73.6 atomic%, Al = 26.4 atomic%) was used as the material of the reaction layer 21.Comparative Example 2In the same manner, an optical recording medium sample of Example 2-3 was produced.
[0091]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 65.7 atomic%, Al = 34.3 atomic%) was used as a material for the reaction layer 21.Comparative Example 2In the same manner, an optical recording medium sample of Example 2-4 was produced.
[0092]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 57.3 atomic%, Al = 42.7 atomic%) is used as the material of the reaction layer 21, and the film thickness of the dielectric layer 15 is set to 30 nm. Other than that,Comparative Example 2In the same manner, an optical recording medium sample of Example 2-5 was produced.
[0093]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 47.7 atomic%, Al = 52.3 atomic%) is used as the material of the reaction layer 21, and the film thickness of the dielectric layer 15 is set to 30 nm. Other than that,Comparative Example 2In the same manner as described above, an optical recording medium sample of Comparative Example 2-1 was produced.
[0094]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 41.2 atomic%, Al = 58.8 atomic%) is used as the material of the reaction layer 21, and the film thickness of the dielectric layer 15 is set to 30 nm. Other than that,Comparative Example 2In the same manner, an optical recording medium sample of Comparative Example 2-2 was produced.
[0095]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 31.9 atomic%, Al = 68.1 atomic%) is used as the material of the reaction layer 21, and the film thickness of the dielectric layer 15 is set to 30 nm. Other than that,Comparative Example 2In the same manner, an optical recording medium sample of Comparative Example 2-3 was produced.
[0096]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 26.4 atomic%, Al = 73.6 atomic%) is used as the material of the reaction layer 21, and the film thickness of the dielectric layer 15 is set to 30 nm. Other than that,Comparative Example 2In the same manner, an optical recording medium sample of Comparative Example 2-4 was produced.
[0097]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 17.8 atomic%, Al = 82.2 atomic%) is used as the material of the reaction layer 21, and the film thickness of the dielectric layer 15 is set to 30 nm. Other than that,Comparative Example 2In the same manner, an optical recording medium sample of Comparative Example 2-5 was produced.
[0098]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 9.4 atomic%, Al = 90.6 atomic%) is used as the material of the reaction layer 21, and the film thickness of the dielectric layer 15 is set to 30 nm. Other than that,Comparative Example 2In the same manner, an optical recording medium sample of Comparative Example 2-6 was produced.
[0099]
  Next, an alloy of titanium (Ti) and aluminum (Al) (Ti = 1.1 atomic%, Al = 98.9 atomic%) is used as the material of the reaction layer 21, and the film thickness of the dielectric layer 15 is set to 30 nm. Other than that,Comparative Example 2In the same manner, an optical recording medium sample of Comparative Example 2-7 was produced.
[0100]
  The reason why the film thickness of the dielectric layer 15 is different for each optical recording medium sample is to make the reflectance of each optical recording medium sample substantially the same.
[0101]
  [Sample Evaluation 2]
  next,Comparative Examples 2, 2-0,The optical recording medium samples of Examples 2-3 to 2-5 and Comparative Examples 2-1 to 2-7 were set in the optical recording medium evaluation apparatus, respectively, and opened while rotating at a linear velocity of 5.3 m / sec. The recording layer 14 (reaction layers 21 and 22) is irradiated with a laser beam having a wavelength of 405 nm through an objective lens having a number of 0.85, and a mixed signal composed of 2T to 8T is used using the pulse train pattern shown in FIG. Was recorded. The pulse width is t_topIs set to 0.5T and t_mpAnd t_lpIs set to 0.4T and t_clWas set to 1.2T. Further, the recording power Pw2 is set to a level at which the jitter is lowest (differs depending on each optical recording medium sample), the intermediate power Pm2 is optimized in the range of 1.6 mW to 2.4 mW, and the base power Pb2 is set to 0. Fixed at 1 mW.
[0102]
  Then, the jitter was measured by reproducing the recorded mixed signal, and the relationship between the amount of aluminum (Al) added to the reaction layer 21 and the jitter was examined. The results are shown in FIG.
[0103]
  As shown in FIG. 11, the jitter was high in the optical recording medium samples of Comparative Examples 2-6 and 2-7, but it was less than 7% in the other optical recording medium samples, and good results were obtained. In particular, the jitter in the optical recording medium samples of Examples 2-3 to 2-5 and Comparative Examples 2-1 to 2-4 was about 6%, and very good results were obtained. From the above, the amount of aluminum (Al) added is set to 0 to 83.atom%Good jitter can be obtained when set to about 25 to 75atom%It was confirmed that a particularly good jitter can be obtained when the level is set to about.
[0104]
  Next, for each optical recording medium sample on which the mixed signal is recorded, the reflectance Rb of the recording mark and the reflectance Rt between the recording marks (blank area) are measured,
(Rt−Rb) / Rt × 100
Thus, the degree of modulation was calculated. The results are shown in FIG.
[0105]
  As shown in FIG. 12, the degree of modulation was low in the optical recording medium samples of Comparative Examples 2-1 to 2-3, but the other optical recording medium samples were 50% or more, and good results were obtained. In particular,Comparative Example 2, 2-3 to 2-5 and Comparative Examples 2-5 to 2-7, the degree of modulation was 60% or more, and very good results were obtained. From the above, it was confirmed that when the addition amount of aluminum (Al) was set to 50 atomic% or less or 80 atomic% or more, a high degree of modulation was obtained.
[0106]
  From the above results, the amount of aluminum (Al) added to the reaction layer 21 is set to 0 to 50.atom%If it is set to about, the jitter and modulation will be good, and 25-50atom%It was found that the jitter and the degree of modulation are particularly good when the degree is set.
[0107]
  Next, each optical recording medium sample was irradiated with a laser beam having a wavelength of 405 nm, and the light transmittance was measured. The results are shown in FIG.
[0108]
  As shown in FIG. 13, the light transmittance was low in the optical recording medium samples of Comparative Examples 2-3 to 2-6, but it was about 50% in the other optical recording medium samples. The light transmittance of the optical recording medium samples of 2-5 and Comparative Example 2-1 was 50% or more. As mentioned above, the addition amount of aluminum (Al) is 25-55.atom%It was confirmed that a particularly high light transmittance could be obtained when the degree was set.
[0109]
  From the above results, the amount of aluminum (Al) added to the reaction layer 21 is set to 0 to 50.atom%Degree, in particular 25-50atom%It was found that the reaction film 21 for the recording layer L1 was suitable if the degree was set.
[0110]
【The invention's effect】
  As described above, according to the present invention, it is possible to provide a write-once type optical recording medium that has good initial characteristics and can store recording information in a good state for a long period of time. Moreover, since the recording layer included in the optical recording medium of the present invention has a high light transmittance, if this is used for an information layer close to the light incident surface in an optical recording medium of a type having a plurality of information layers, the information in the lower layer is used. It becomes possible to improve the recording / reproducing characteristics for the layer.
[Brief description of the drawings]
1A is a cutaway perspective view showing an appearance of an optical recording medium 10 according to a preferred embodiment of the present invention, and FIG. 1B is an enlarged partial sectional view of a portion A shown in FIG. .
FIG. 2 is a schematic cross-sectional view showing an enlarged main part of the optical recording medium 10;
FIG. 3 is a schematic cross-sectional view showing an enlarged region where a recording mark M is formed.
4A and 4B are diagrams showing a preferable example of a pulse train pattern of a laser beam L for recording data on the optical recording medium 10. FIG. 4A shows a pulse train pattern when a 2T signal is formed, and FIG. ) Shows a pulse train pattern when a 3T signal is formed, (c) shows a pulse train pattern when a 4T signal is formed, and (d) shows a pulse train pattern when a 5T signal to 8T signal is formed. .
FIG. 5 is a partial sectional view of an optical recording medium 30 according to another preferred embodiment of the present invention.
FIG. 6 is a schematic cross-sectional view showing an information layer L1 in an enlarged manner.
7 is a schematic cross-sectional view showing, in an enlarged manner, a region where a recording mark M is formed in the information layer L1.
FIG. 8 is a diagram showing a preferable example of a pulse train pattern of a laser beam L for recording data on the information layer L1 of the optical recording medium 30. FIG. 8A shows a pulse train pattern when a 2T signal is formed. (B) shows a pulse train pattern when a 3T signal is formed, (c) shows a pulse train pattern when a 4T signal is formed, and (d) shows a pulse train pattern when a 5T signal to 8T signal is formed. Is shown.
FIG. 9 is a graph showing a change in reflectance with progress of a storage test.
FIG. 10 is a graph showing a change in jitter accompanying the progress of a storage test.
11 is a graph showing the relationship between the amount of aluminum (Al) added to the reaction layer 21 and jitter. FIG.
12 is a graph showing the relationship between the amount of aluminum (Al) added to the reaction layer 21 and the degree of modulation. FIG.
13 is a graph showing the relationship between the amount of aluminum (Al) added to the reaction layer 21 and the light transmittance. FIG.
[Explanation of symbols]
10, 30 Optical recording medium
11, 31 Support substrate
11a, 31a, 32a groove
11b, 31b, 32b land
12 Reflective layer
13, 15 Dielectric layer
14 Recording layer
16, 33 Light transmission layer
16a, 33a Light incident surface
21,22 Reaction layer
32 Transparent intermediate layer
L Laser beam
L0, L1 information layer

Claims (5)

The recording layer includes at least a substrate and a recording layer provided on the substrate. The recording layer includes a first reaction layer containing titanium (Ti) as a main component, silicon (Si), germanium (Ge), and carbon (C ), tin (Sn), gold (Au), zinc (Zn) and copper (see contains a second reaction layer containing one element selected from the group consisting of Cu) as a main component, the first An optical recording medium , wherein 25 atomic% or more and less than 50 atomic% of aluminum (Al) is added to the reaction layer . The optical recording medium according to claim 1, further comprising first and second dielectric layers provided so as to sandwich the recording layer . 3. A light transmission layer provided on the opposite side of the substrate as viewed from the recording layer, wherein the light transmission layer has a thickness of 10 to 300 μm. An optical recording medium according to 1 . 4. The optical recording medium according to claim 1, wherein data can be recorded by irradiation with a laser beam having a wavelength of 380 nm to 450 nm . The recording layer includes a substrate and a plurality of information layers provided on the substrate, and the recording layer included in a predetermined information layer different from the information layer farthest from the light transmission layer among the plurality of information layers is titanium (Ti ) And a group consisting of silicon (Si), germanium (Ge), carbon (C), tin (Sn), gold (Au), zinc (Zn), and copper (Cu). look contains a second reaction layer containing as a main component more selected one element, the first reaction layer 25 atomic percent or more, that of less than 50 atomic% of aluminum (Al) is added A characteristic optical recording medium.

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